You always want to have reliable communication devices when heading out in a boat. But these days, your mobile phone can do a lot more than just make emergency calls.

Most mobile phones now come with a GPS receiver, so an option like Google Maps will work. But you’re relying on a cell-phone signal or wireless service, you may be out of luck. And remember enabling your phone’s GPS will eat up the battery quickly.

For navigating in open water, the Marine & Lakes: USA app overlays nautical charts onto a map database. If you exit a service zone, the app will have already downloaded, so it can work without a signal.

Another option called iNavX is a popular charting app for the iPhone and iPad.

And then there are the non-navigational options. One called Boating Suite helps you keep track of boat maintenance, expenses, and fuel use.

And here’s a fun one: The iKnots app is a simple way to learn all the important sailing knots. The app has animated and written explanations to teach you how to tie the right knots for the right situation.